Implosion-proof cathode-ray tube and method of making same

ABSTRACT

An implosion proofing means including a conductor in the form of a metal wire or strip and a binder covering the conductor is disposed on a suitable portion of the outer peripheral face of the sidewall or the peripheral edge of the faceplate of the bulb of a cathode-ray tube and then current is supplied to the conductor to fuse the binder so that the implosion proofing means including the conductor core can be securely fixed to that portion of the bulb to provide an implosion-proof cathode-ray tube.

United States Patent Takemoto et al.

[54] IMPLOSlON-PROOF CATHODE-RAY TUBE AND METHOD OF MAKING SAME [72] Inventors: Takeo Takemoto; Yoshihiko Mlyata; Takao Kawamura, all of Mobara-shi,

Japan [73] Assignee: Hitachi, Ltd, Tokyo, Japan [22] Filed:

Jan. 2, 1970 [21] Appl.No.: 363 i [30] Foreign Application Priority Data Jan. 6, 1969 Japan ..44/48 Jan. 6, 1969 Japan... ..44/4l [52] US. Cl ..l78/7.82, 178/7.82, 220/21 [51] Int. Cl. ..H04n 5/64 [58] Field ol'Search ..l78/7.8, 7.82; 220/21 A, 2.3 A;

[ 5] Mar. 7, 1972 [56] Relerenees Cited UNITED STATES PATENTS 2,860,328 11/1958 Langworthy ..178/7.82 2,907,914 10/1959 Brownell 3,166,211 1/1965 Stel ..178/7.82 3,403,805 10/1968 Powell ..220/2.l A

Primary Examiner-Robert L. Griffin Assistant Examiner-Joseph A. Orsino, .lr. AttorneyCraig, Antonelli & Hill [57] ABSTRACT An implosion proofing means including a conductor in the form of a metal wire or strip and a binder covering the conductor is disposed on a suitable portion of the outer peripheral face of the sidewall or the peripheral edge of the faceplate of the bulb of a cathode-ray tube and then current is supplied to the conductor to fuse the binder so that the implosion proofing means including the conductor core can be securely fixed to that portion of the bulb to provide an implosion-proof cathode-ray tube.

5 Claims, 3 Drawing Figures Patented March 7, 1972 3,647,960

INVENTOR5 THKEO TAKE/0T0 YOSHIHIKO MIYATA a d TRKAD KAWAMHRA ATTORNEYS lMPLOSION-PROOF CATI-IODE-RAY TUBE AND METHOD OF MAKING SAME BACKGROUND OF THE INVENTION 1. Field of'the Invention This invention relates to a cathode-ray tube provided with improved implosion proofing means and a method of making such a cathode-ray tube. More particularly, it relates to the structure of an implosion-proof cathode-ray. tube which is safeguarded from the danger due to implosion thereof and a method of making such acathode-ray tube.

2. Description-of the Prior Art Theshape of a cathode-ray tube is such that the bulbhas the greatest diameter at a portion-corresponding tothe screen and the sidewall of the bulb terminate in the funnel portion of a gradually converging configuration. In view of such a shape of the cathode-ray tube, a large tensile-strain is developed at the sidewall portion in the'circumferential direction of the bulb. Thus, the bulb is very susceptible to cracks at this side wall portion and the'presence of a slightest scratch at this portion tends to increase the danger of implosion.

In an attempt to prevent the objectionable implosion, various means have heretofore been proposed. For example, Japanese Pat. publication, No. 17937/1963 discloses an implosion proofing means according to which a metal ring is disposed to surround the sidewall of the glass bulb and a binder such as a thermo-setting synthetic resin is injected intothe space between the bulb .and the metal ring. Further, US. Pat. Nos. 3,220,592 and 3,220,593 disclose an implosion proofing means according to which a rim is bonded to the glass bulb and a band is used to fasten the rim onto the glass bulb. However, the former means in which a binder is injected into the space between the metal ring and the bulb is defective in that the external shape of the cathode-ray tube is increased due to the fact that the inside diameter of the metal ring must be slightly larger than the outside diameter of the glass bulb and a suitable jig must be used to support the metal ring in place until the injected binder has completely solidified. The former means is further defective in that the injected binder may flow out of the space during the heating thereof before it solidifies and may become attached to other portions of the glass bulb. The latter means employing a fastening band is also defective in that the binder existing between the rim and the glass bulb may be squeezed outside during the fastening of the band and difficulties are encountered in removing the binder thus squeezed out.

Japanese Pat. publication, No. 8791/1963 proposes a method of implosion proofing a cathode-ray tube which comprises coiling a glass cord around the side wall portion of the bulb of the cathode-ray tube while directing a spray of polyester resin onto the bulb, pressing the glass cord against the bulb and covering the glass cord with a layer of a synthetic resin containing fibers so that the layer makes a sufficiently strong bond to the bulb to render the bulb adequately resisting to implosion. However, such a method is defective in that the coiling of the glass cord around the bulb while spraying the resin and the separate application of the binder and the implosion proofing member to the bulb result in a very complex operation and the resin tends to be distributed over rather a more wider range than is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an implosion-proof cathode-ray tube of improved structure which is free from the various defects encountered with the prior art implosion-proof cathode-ray tubes as described above.

Another object of the present invention is to provide a novel method of implosion proofing a cathode-ray tube.

In accordancewith the present invention, there is provided an improved implosion-proof cathode-ray tube comprising an implosion proofing means including a conductor core in the form of a metal wire or strip and a binder applied to the surface of said core, said implosion proofing means being disposed on a suitable portion of the outer peripheral face of the sidewall or on a suitable portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube, said core being securely fixed to said portion of the bulb by the binder which is fused and then solidified.

Other objects, features and advantages of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partly sectional side elevational view of an embodiment of the improved implosion-proof cathode-ray tube according to the presentinvention.

FIG. 2 is an enlarged perspective view of an implosion proofing means preferably employed in the improved implosion-proof cathode-ray tube according to the present invention.

FIG. 3 is a partly sectional side elevational view of another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 showing an embodiment of the present invention, an implosion proofing member 6, the detail of which is illustrated in FIG. 2, is coiled around the outer peripheral face of the sidewall 2 of a cathode-ray tube 1 by a plurality of turns in such a manner that suitable spacings are defined between the convolutions to prevent any undesirable short circuit between the adjacent convolutions of the member 6.

FIG. 2 shows an example of the implosion proofing member 6 preferably used in the implosion-proof cathode-ray tube according to the present invention. Referring to FIG. 2, the outer surface of a conductor core 3 which may, for example, be an iron or a copper wire covered with a layer 4 of electrical insulator such as urethane, and a binder 5 of thermoplastic or thermo-setting resin such as epoxy resin is applied to the outer surface of the insulator layer 4 to constitute the implosion proofing member 6.

After coiling the implosion proofing member 6 around the side wall 2 of the cathode-ray tube 1, current is supplied to the core 3 of the implosion proofing member 6 to fuse the binder 5 covering the core 3 so as to securely fix the core 3 to the side wall 2 of the cathode-ray tube 1 by the binder 5.

Referring to FIG. 3 showing another embodiment of the present invention, an implosion proofing member 6 as shown in FIG. 2 is bonded to a portion 7 adjacent to the peripheral edge of the face plate of a cathode-ray tube 1.

A method of implosion proofing for obtaining an implosionproof cathode-ray tube having the structure shown in FIG. 1 will be described.

At first, the implosion proofing member 6 is prepared by covering the outer surface of a conductor core 3 which may, for example, be a wire of iron or copper with a layer 4 of electrical insulator such as urethane and applying to the outer surface of the insulator layer 4 a binder 5 of a thermoplastic or a thermo-setting resin, such as an epoxy resin. The implosion proofing member 6 is coiled around the outer peripheral face of the side wall 2 of a cathode-ray tube 1 by a plurality of turns in such a manner that a suitable spacing is defined between the convolutions to prevent an undesirable short circuit between the adjacent convolutions of the conductor core 3. In coiling the implosion proofing member 6, tension need not be especially applied, but the application of tension to the member 6 is preferable in that a higher implosion proofing effect can be expected.

The ends 3a and 3b of the conductor core 3 exposed at opposite ends 6a and 6b of the implosion proofing member 6 coiled around the outer peripheral face of the sidewall 2 are then connected to an external power supply (not shown) and current is supplied to the conductor core 3. Joule heat is developed in the core 3 by the current supplied to the core 3 and the binder 5 applied to the outer surface of the core 3 is fused by the Joule heat. The fused binder 5 adheres to the outer peripheral face of the sidewall 2 of the cathode-ray tube 1, and upon cutting off the current supplied to the core 3, the binder 5 solidifies to securely fix the core 3 to the outer peripheral face of the side wall 2 of the cathode-ray tube 1 thereby forming an implosion-proof structure.

A method of implosion proofing for obtaining the cathoderay tube of the present invention shown in FIG. 3 will next be described. In FIG. 3, an implosion proofing member 6 of the kind described above is bonded to a portion 7 adjacent to the peripheral edge of the face plate of a cathode-ray tube 1. In this case, the implosion proofing member 6 may be bonded to such a portion 7 in a manner similar to that described above. Alternatively, the implosion proofing member 6 may be coiled to conform to the curved contour of the portion 7 adjacent to the peripheral edge of the face plate and subjected to preliminary heating to obtain a frame structure, and the frame structure may be fitted on the peripheral edge portion 7 of the face plate, current being then supplied to the core 3 to fuse the binder 5 thereby to bond the core 3 to the desired portion 7 by the binder 5.

The insulator layer 4 in the implosion proofing member 6 is provided to prevent an undesirable short circuit between the adjacent convolutions of the core 3 during heating of the core 3. The insulator layer 4 may be eliminated depending on the properties of the binder.

It will be understood from the foregoing description that the present invention provides a method of implosion proofing member 6 is provided to prevent an undesirable short circuit between the adjacent convolutions of the core 3 during heating of the core 3. The insulator layer 4 may be eliminated depending on the properties of the binder.

It will be understood from the foregoing description that the present invention provides a method of implosion proofing a cathode-ray tube comprising preparing an implosion means including a conductor core in the form of a metal wire or strip and a binder covering the surface of said core, coiling said implosion proofing means around a suitable portion of the outer peripheral face of the sidewall or a suitable portion adjacent to the peripheral edge of the face plate of the glass bulb of the cathode-ray tube in such a manner that the adjacent convolutions of said core are suitably spaced apart to prevent an undesirable short circuit therebetween, and supplying current to said core to the desired portion of the glass bulb by said binder. The present invention is advantageous in that it obviates the need for preparing a large-sized implosion proofing frame which has a large inside diameter to allow for injection of the binder into the space between the frame and the glass bulb. Thus, any undesirable increase in the size of the cathode-ray tube can be avoided and trouble due to squeezing of the binder out of the implosion proofing frame can be obviated. The present invention is further advantageous in that as there is very little possibility of the binder flowing out, no special jig is required for the implosion proofing, and the binder and the implosion proofing member can be integrally handled, which facilitates the implosion proofing work remarkably. Another advantage is that the performance of the cathode-ray tube is not impaired at all because there is no need of the process of heating the cathode-ray tube in a heating furnace. Further, the implosion-proof cathode-ray tube made according to the method of the present invention has a simple and strong structure while sufficiently attaining the object of preventing the danger of implosion.

We claim:

1. An implosion-proof cathode-ray tube comprising an implosion proofing means including a conductor core in the form of a metal wire or strip and a binder applied to the surface of said core, said implosion proofing means being disposed on at least one of predetermined portions including a portion of the outer peripheral face of the sidewall and a portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube, said core being securely fixed to said portior 1 of the bulb by said binder which is fused and then solidified, in which said implosion-proofing means including said core is coiled around at least one of the predetermined portions including a portion of the outer peripheral face of the side wall and a portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube and said core is securely fixed to said portion of the bulb with the adjacent convolutions of said core being electrically insulated from each other.

2. An implosion-proof cathode-ray tube according to claim 1, further including an insulator disposed between said metal wire or strip and said binder.

3. A method of implosion proofing a cathode-ray tube comprising the steps of;

preparing an implosion proofing means including a core in the form of an elongated metal conductor and a binder applied to the surface of said core;

coiling said implosion proofing means around at least one of the predetermined portions including a portion of the outer peripheral face of the sidewall and a portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube;

supplying current to the core of said implosion proofing means to fuse said binder by heating same; and

allowing said binder to solidify to securely fix said core to said portion of the bulb by said binder.

4. A method of implosion proofing a cathode-ray tube as claimed in claim 3, in which said conductor core of said implosion proofing means is in the form of a metal wire or strip, and the adjacent convolutions of said core coiled around said bulb are electrically insulated from each other.

5. A method of implosion proofing a cathode-ray tube comprising the steps of;

preparing an implosion proofing means including a core in the form of an elongated metal conductor and a binder applied to the surface of said core in an electrically insulated relation from said core; coiling said implosion proofing means to a shape conforming to the curved contour of a portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube and subjecting said implosion proofing means to preliminary heating to obtain a frame structure;

fitting said frame structure on the portion adjacent to the peripheral edge of the face plate;

supplying current to the core of said implosion proofing means shaped as said frame structure thereby to fuse said binder by heating same; and

allowing said binder to solidify to securely fix said core to said portion of the bulb by said binder. 

1. An implosion-proof cathode-ray tube comprising an implosion proofing means including a conductor core in the form of a metal wire or strip and a binder applied to the surface of said core, said implosion proofing means being disposed on at least one of predetermined portions including a portion of the outer peripheral face of the sidewall and a portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube, said core being securely fixed to said portion of the bulb by said binder which is fused and then solidified, in which said implosion-proofing means including said core is coiled around at least one of the predetermined portions including a portion of the outer peripheral face of the side wall and a portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube and said core is securely fixed to said portion of the bulb with the adjacent convolutions of said core being electrically insulated from each other.
 2. An implosion-proof cathode-ray tube according to claim 1, further including an insulator disposed between said metal wire or strip and said binder.
 3. A method of implosion proofing a cathode-ray tube comprising the steps of; preparing an implosion proofing means including a core in the form of an elongated metal conductor and a binder applied to the surface of said core; coiling said implosion proofing means around at least one of the predetermined portions including a portion of the outer peripheral face of the sidewall and a portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube; supplying current to the core of said implosion proofing means to fuse said binder by heating same; and allowing said binder to solidify to securely fix said core to said portion of the bulb by said binder.
 4. A method of implosion proofing a cathode-ray tube as claimed in claim 3, in which said conductor core of said implosion proofing means is in the form of a metal wire or strip, and the adjacent convolutions of said core coiled around said bulb are electrically insulated from each other.
 5. A method of implosion proofing a cathode-ray tube comprising the steps of; preparing an implosion proofing means including a core in the form of an elongated metal conductor and a binder applied to the surface of said core in an electrically insulated relation from said core; coiling said implosion proofing means to a shape conforming to the curved contour of a portion adjacent to the peripheral edge of the face plate of the bulb of the cathode-ray tube and subjecting said implosion proofing means to preliminary heating to obtain a frame structure; fitting said frame structure on the portion adjacent to the peripheral edge of the face plate; supplying current to the core of said implosion proofing means shaped as said frame structure thereby to fuse said binder by heating same; and allowing said binder to solidify to securely fix said core to said portion of the bulb by said binder. 